ABSTRACT 2019 marks the 12th year of The Ribble Trusts inter- annual fisheries monitoring programme. Results and observations from this work helps inform the trust on the productivity of sub-catchment fisheries and where to direct conservation efforts.
Adam Wheeler Fisheries Monitoring Officer FISHERIES MONITORING OF THE RIBBLE CATCHMENT 2019 The Ribble Rivers Trust
Fisheries Monitoring of the Ribble Catchment
Ribble Rivers Trust C/O Hanson Cement Ribblesdale Works Clitheroe BB7 4QF
Phone: 01200 444452 E-mail: [email protected]
Report title: Fisheries Monitoring of The Ribble Catchment 2019 Report reference: RRT_ Electric_Fishing _2019_Report Report version: 1.0 Date: 01/11/2019 Prepared for: Ribble Rivers Trust Authored by: Adam Wheeler - Fisheries Monitoring Officer Checked by: Mike Forty - Catchment Science Coordinator
Copyright Ribble Rivers Trust, 2019.
This report has been prepared using due skill, care and diligence for the exclusive use of the commissioning party by Ribble Rivers Trust. No liability is accepted by Ribble Rivers Trust for the use and or application of the contents of the report. Fisheries Monitoring of the Ribble Catchment
Table of Contents Acknowledgments ...... i Executive Summary ...... 1 Introduction ...... 1 Fishery Results 2019 ...... 3 1.0 Introduction ...... 6 1.1 Sub-Catchment Map ...... 7 2.0 Methodologies...... 8 2.1 Electric fishing Surveys ...... 8 3.0 Monitoring Results ...... 10 3.1 Brown Trout (Salmo trutta) ...... 10 The Calder Catchment ...... 13 The Hodder Catchment ...... 15 The Lower Ribble Catchment ...... 17 The Mid-Ribble Catchment ...... 18 The Upper Ribble Catchment ...... 20 3.2 Atlantic Salmon (Salmo salar) ...... 22 The Calder Catchment ...... 25 The Hodder Catchment ...... 26 The Mid-Ribble Catchment ...... 28 The Upper Ribble Catchment ...... 30 3.3 Other Species ...... 32 3.4 Length-Weight Relationships and Biomass ...... 35 Condition Factor ...... 35 Biomass ...... 39 4.0 Discussion ...... 41 5.0 References ...... 43 6.0 Appendices ...... 45 6.1 Appendix A ...... 45 6.2 Appendix B ...... 46 6.3 Appendix C ...... 50
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Acknowledgments
The core fisheries monitoring of the Ribble catchment has been supported and funded by Ribble Rivers Trust and its members. Funding has also been issued from the England European Regional Development Fund as part of the European Structural and Investment Funds Growth Programme 2014-2020, for the monitoring of the Primrose Lodge Blue and Greenway project. We are grateful to all involved landowners for their permission to land-access and look forward to continued cooperation for future work. The Ribble Trust wishes to thank the following researchers, staff, and volunteers whose help and continued enthusiasm has proved invaluable during this year’s survey program: Ellie Brown, Mike Forty, Helen Smith (RRT); Kate Cartmell Done and Kate Morgan (RRT, Seasonal Survey Assistants); Lynn Yates, Marco Dobson, Paul Sharples, Tony Cookson Lucy Wilde (Electric Fishing Volunteers).
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Executive Summary
Introduction The Ribble Rivers Trust has concluded the 12th year of its fisheries monitoring programme of the Calder, Hodder and Ribble catchments. Additional and repeat surveys have also been performed on the River Darwen to continue the capital work assessment from the Ribble Life Together programme.
The methodology applied in the fisheries programme uses quantitative and semi-quantitative surveys to assess catchment salmonid productivity using an adapted Crozier and Kennedy (1994) electric fishing method. For 2019 an improvement to the programme’s methodology has been made, Zippin’s (1956,1958) K-Pass Removal method has been applied to increase the accuracy of density estimations. This methodology has also been applied to previous years data (2008-2018) to make it comparable and allow for trends to be observed.
As juvenile fish densities change rapidly with age, surveys are conducted at a similar time each year (June – October) and in the same area to allow for valid comparisons. A total of 328 sites were surveyed in 2019 covering 5 sub-catchments. Salmonids are a keystone species within the river system, they rely on ecological stability and are indicators of water and habitat quality. The Ribble Trust uses the National Fisheries Classification Scheme (NFCS) to allow for the standardisation of results by grading sites based on the densities of fry comparable to the national dataset. Results of electric fishing surveys are used to support and identify future works as well as monitoring the long-term impacts of migration and habitat restoration schemes.
With anthropogenically driven climate change, we are seeing more extreme weather patterns, increased probability of high intensity rainfall events and longer dry periods. With the summer of 2018 dominated by warm weather and below average rainfall, drought conditions were seen across the Ribble catchment. Mean temperatures of 17.2°C were documented by the Met Office making it the hottest summer on record. There were concerns for the +0 salmonids targeted during the 2018 survey season, as fry are more sensitive to extremely low flows due to poor mobility and ability to seek refuge. Overall the UK had 48% of average rainfall of the 1981-2010 average during the summer months and by the end of October groundwater and river levels remained below average. 2018 Summers lowest flows coincided with the main run of sea trout in July and in the Autumn months minimal spate events took place from the end of September (Figure 1).
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Figure 1. Average river levels on the River Ribble at Samlesbury, January - December 2017 & 2018.
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February 2019 saw unseasonably warm weather and was recorded as the hottest on record for the UK. Rainfall was exceptionally high for the North West in March with Storms Freya, Gareth, and Hannah bringing bands of heavy rainfall and high winds. This resulted in flood warnings being issued and some of the highest river levels recorded since the winter of 2015 (Figure 2). By the month-end, half of the hydrological areas in North West England had observed around twice the expected monthly rainfall for March. 6 2019 Average Level 2019 Max Level 5 4 3 2 1 0 J F M A M J J A S O N A E A P A U U U E C O N B R R Y N L G P T V
Figure 2. Average and max river levels of the River Ribble, January to October 6th, 2019
The timing and patterns of emergence and the size of emerging fish has high importance on their subsequent establishment of feeding territory, further dispersal and survival potential. Mortality bottlenecks for many species occur in juvenile stages and are thought to result from limitations of food or foraging habitat during a "critical period" for growth and survival. For salmonids the largest proportion of mortalities occur during the first weeks of fry emergence after depletion of yolk reserves and feeding begins. These high flow events in March 2019 occurred at this critical time for salmonid development. Mortalities of salmonids can increase significantly with high discharge events due to their size affecting swimming ability. Events like this also have a negative effect on growth as spate events reduce the abundance of food.
With these extreme events in combination with 2015 flood events depleting the 2016 cohort, we have recorded the worst fry recruitment on the catchment in 12 years of surveys. Although fish communities have evolved to withstand the dynamic nature of a river habitat and are relatively resilient to high hydrological events, severe floods and extreme low flows at critical life-cycle stages influence community composition which have short and long term affects, especially when looking at species of concern.
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Fishery Results 2019
In 2019 brown trout productivity on all catchments has crashed after the effects of extreme weather events over the past 4 years (Figure 3).In 2018 brown trout (Salmo trutta) were found present in 75% of sites surveyed and 69% of sites produced fry. These were recorded in some of the best densities in the 12 years of RRT fisheries surveys. Results show a decrease in brown trout presence in 67% of sites with only 42% producing fry. The question is how will this year impact the parr populations of 2020, the future adult spawning population and how will this cohort impact recruitment once sexually mature?
From the Calder, Hodder and Ribble results, sites that have seen an improvement in trout fry densities are mainly in areas
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Figure NFCS Cumulative gradescore 3. Total grade-score for all sub-catchment electric fishing sites with 10 years of consecutive brown trout data 0 2010 to 2019 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Calder Hodder Ribble that have previously been recorded as poor or very poor and largely remain as such. The increased number of sites on the catchment that have been recorded as having an absence of trout fry are of concern, especially in areas where they have previously been documented in high densities. Only one site has seen a reasonable increase in trout fry densities, which is a location upstream of the Langden Brook intake on the Hodder catchment which has increased 4 NFCS grades from E to B. In the last week of August fresh run sea trout were recorded on the River Dunsop after spate events. It is rare to capture sea trout in RRT surveys and to observe them in 2019 is a positive after the prolonged low waters during last year’s peak migration time. River discharge and water levels play an important role in both timing and success of fish ascent, and sea trout can contribute to a large proportion of ova production during spawning in comparison to resident fish.
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The Ribble, once considered a premium English salmon water, is very much a salmon population that is at risk. 2019 shows the lowest recruitment the catchment has seen in 12 years of Ribble Trust monitoring (Figure 4). If the degradation of Atlantic 180 160 140 120 100 80 60 40 Cumulative NFCS NFCS Cumulative gradescore 20 0 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Atlantic salmon
Figure 4. Cumulative NFCS grade-score and total calculated fry/100m² for the catchments 158 electric fishing sites holding 10 years of consecutive data for Atlantic salmon 2010 - 2019. salmon populations continues at this rate it could lead to unrecoverable numbers and local extinction on the Ribble and its sub-catchments. The year on year decline of the cumulative grade score is driven by the loss of low-density sites which has narrowed the distribution of salmon spawning. Sites that have also been classed as ‘strongholds’ for Atlantic salmon are also being impacted by poor returns. These areas must be protected and an increase in conservational efforts must be applied to improve habitat and water quality if we are to have long-term sustainability of the species.
20 90 18 80 16 70 14 60 12 50 10 40 8 30 6 4 20 Cumulative NFCS NFCS Cumulative gradescore 2 10 0 0 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019
Calder Hodder Ribble Figure 5. Total grade-score for all sub-catchment electric fishing sites with 10 years of consecutive Atlantic salmon data 2010 to 2019 It seems there has been little change on the Hodder catchment from the long-term trends (Figure 5), however, this only shows the sites that have 10-years of consecutive data. There are holes in the long-term data set representing sites on the River Dunsop, Brennand and Whitendale. These tributaries are classed as stronghold sites which regularly produce good densities of young, but this year the River Dunsop has seen some of the largest reductions in NFCS grade scores on the Hodder
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Fisheries Monitoring of the Ribble Catchment catchment, which is not reflected in the 10-year trend. The Calder catchment did not produce any salmon fry in 2019, but two salmon parr were recorded on the lower reaches of Sabden Brook. Environmental DNA sampling has been carried out in 2019 to try and identify the potential upstream limits of salmon on the Calder catchment. Initial results have shown indications that Atlantic salmon are present on Pendle water and investigation surveys will take place in 2020. One positive outcome in this year’s monitoring is that Atlantic salmon have been recorded spawning by the trust for the first time in West Bradford Brook, above a 2018 fish pass. It is thought that salmon could get to this location previously in elevated flows, but this is the first salmon fry recorded in 12 years of electric fishing surveys.
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1.0 Introduction
The Ribble Rivers Trust (RRT) has been conducting habitat restoration schemes and facilitating improved land management within the Ribble catchment for over twenty years with the aim to preserve a healthy system which in turn will provide resources and habitat to support and sustain strong populations and increase biodiversity.
This year concludes the trusts 12th year of annual electric fishing surveys across 328 selected sites which encompasses 5 sub- catchments of the Ribble: Calder, Darwen, Hodder, Lower Ribble and Upper Ribble (Figure 1.1). From the 328 sites there are 94 core sites which have 12 years of consecutive data and 158 sites that have 10 years of consecutive data. Additional electric fishing surveys have also been conducted by the Environments Agency (EA) as part of their core fisheries monitoring programme. Under a data sharing agreement, the EA results from overlapping sites are included in the analysis of this report as the NFCS grades standardise results and are comparable to RRT outputs.
Principally, our continuing aims are to: -
1. Assess the overall status of the juvenile population of salmonids. 2. Monitor the inter-annual variations of the salmonid young of year population. 3. Determine underperforming areas and direct improvement works. 4. Capture the effectiveness of previous habitat improvement works. 5. Generate data and evidence in support of and to report on grant bids and applications. 6. Generate knowledge of rare species to inform responsible development. 7. Locate ecological threats posed by invasive species. 8. Derive future research questions
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1.1 Sub-Catchment Map
Figure 1.1. River Ribble catchment map displaying sub-catchment boundaries and reference locations.
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2.0 Methodologies
2.1 Electric fishing Surveys
The Trusts applied methodology is adapted from Crozier and Kennedy (1994) and has been in operation since 2008. Riffle/pool habitat is targeted to capture both the young of year and the +1 populous of salmonids using an electric fishing backpack system. Two types of survey are undertaken: semi-quantitative, where the river is actively fished for five minutes covering a measured un-isolated area; and quantitative, where a demarcated area of river is sampled over sequential depletive passes. Each survey is fished upstream in alternating widths with the anode swept through the water column, matching the rate of flow, towards a netter. Salmonid fork lengths are recorded in millimeters at each site and the weight of individuals documented during quantitative surveys to the nearest gram. The abundance of other species is noted and the total weight in grams of each species is recorded in quantitative surveys. As juvenile fish densities change rapidly with age, surveys are conducted at a similar time each year and in the same area to allow for valid comparisons.
For 2019, 328 survey sites were identified for assessment with priority given to sites that hold the most significant data set, with six or more years of continuous data or in key locations for monitoring restoration works. Prior to the 2019 survey programme the Ribble Rivers Trust coordinated with the EA to avoid a duplication of efforts. Commencing from 17th June and closing on 2nd October, 6 quantitative sites were fished on the Calder (6 in 2018), 6 on the Hodder (4 in 2018), and 12 completed on the Ribble (11 in 2018). A total of 304 semi- quantitative surveys were performed (312 in 2018).
From the above activities the young of year are determined by establishing a maximum fork length discerned from the frequency-length distribution of the species. This method is applied to each major catchment individually to reflect the temporal and spatial differences in fry as the electric fishing season progresses (Appendix B.1 – B.7). Quantitative surveys provide fry densities per 100m² from the depletion of a known measured area, these densities are generated from Zippin’s (1956,1958) K-Pass Removal method, whereas, semi-quantitative results are calculated from the number of fry captured in an active five minutes. The equation applied to the semi- quantitative results is formed from the quantitative fry population relationship between a 5 minutes fry capture in the first pass and the total electric fishing result (fry per 100m²) (Appendix C.1 and C.2). Data used must reflect the variation in fishing results based on the constant effort of the electric fishing team for each site surveyed. This relationship uses quantitative data collected as well as the addition of a zero, zero point to represent a total absence of salmonids. The resulting equation is taken from the fitted linear regression for 0 + salmonids where:
푙푛(푦 + 1) = 푎 + 푏 푙푛(푥 + 1)
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The densities of trout and salmon fry per 100m² are allocated a grade-score (Table 1) which standardises the Trust’s field observations with those of the National Fisheries Classification System (NFCS).
Table 2.1 National Fisheries Classification System for trout and salmon fry density per 100m²
Grade Description Trout fry per 100m² Salmon fry per 100m²
A Excellent >38 >86
B Good 17 – 38 45 – 86
C Fair 8 – 16 23 – 44
D Poor 3 – 7 9 – 22
E Very Poor 1 – 2 1 – 8
F No Fish Present 0 0
Graded results are transferred to a map layer using ArcGIS 10.3.1 to display catchment scale results. Within the result section the inter-annual comparison of data is based on sites which hold 10 years of consecutive data and the grade change evaluation is the comparison of all sites fished in both 2018 and 2019. Grade results have been organised within the analysis of this report according to geographical coverage determined by sub-catchment.
Maps incorporate the following data files under copyright: © Environment Agency copyright and / or database rights 2019. All rights reserved; © Natural England copyright. Contains Ordnance Survey data © Crown copyright and database right 2019. Base-map imagery sources: National Geographic, Esri, DeLorme, HERE, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, increment P Corp. All maps © 2019, Ribble Catchment Conservation Trust.
All images © 2019, Ribble Rivers Trust.
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3.0 Monitoring Results
3.1 Brown Trout (Salmo trutta)
During the surveys of 2019, a total of 1,952 fry, parr and adult brown trout were captured in 222 out of the 328 electric fishing sites, which is a decrease of 2,270 individuals compared to 2018. Fluctuations in brown trout populations have been observed over the past 9 years. However, recruitment on the catchment has crashed in 2019 as populations are impacted from recent extreme weather events. There are concerns to be had over how this year’s fry population will affect future spawning on the catchment and how many generations it will take for full recovery to be seen (Figure 3.1.1). Recovery of trout fry densities have been observed previously after spawning was disrupted and high fluvial events caused red washout in the winter of 2015. This could also be one of the factors which has reduced the spawning success and fry densities of this year.
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50 50 Cumulative NFCS NFCS Cumulative gradescore 0 0 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Calder Hodder Ribble Figure 3.1.1. Total brown trout grade-scores for sub-catchment electric fishing sites with 10 years of consecutive data 2010 to 2019 (158 sites in total)
The increased number of sites on the catchment that have been recorded as having an absence of trout fry are of concern, especially in areas where they have previously been documented in high densities. Brown trout provide one of the best indicators of a catchment’s health due to the majority of individuals spending their lifecycle residing in the river system. This crash is a reminder of how extreme events, which are becoming more frequent, can have a large impact on populations.
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0 ABCDEF
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Figure 3.1.2. Frequency comparison of brown trout NFCS grades in the Ribble catchment 2017 to 2019 (F=0)
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Figure 3.1.3. Catchment map [1:250,000] showing brown trout fry NFCS grades from surveys undertaken by RRT in 2018. Green to red points indicate higher to low grades. Black indicates an absence of trout fry.
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Figure 3.1.4. Catchment map [1:250,000] showing brown trout fry NFCS grades from surveys undertaken by RRT in 2019. Green to red points indicate higher to low grades. Black indicates an absence of trout fry.
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The Calder Catchment
In 2018 the Calder catchment saw a peak in trout fry 25 densities where 79% of site surveyed contained 20 young of year. In comparison only 46% of sites 15 10 produced fry in 2019 with some of the lowest
5 Number sites Number of densities ever recorded on the catchment. 0 Previously the locations that were recorded as -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 Calder brown trout grade change from 2018 to 2019 having no trout fry on the Calder catchment were observed in areas with low or poor spawning Figure 3.1.5. NFCS grade change comparison of brown trout on the Calder catchment 2018 to 2019 (0 = no change). potential. In comparison there has been a large shift this year where normally productive sites have failed to produce young (Figure 3.1.5), with Pendle Water, The Don sub- catchment and sites on Sabden Brook having the largest decrease in trout fry densities (Figure 3.2.7). From the 2019 surveys on this catchment there were only 2 sites that have an improved NFCS grade scores, but these were only from F grades to E grades. Sites that have shown no change in NFCS grade from 2018 to 2019 were already absent of trout fry. The reduction and absence of trout fry this year is the lowest recruitment this catchment has seen in the 12 years of the Trusts fisheries programme.
The Calder is a recovering industrial catchment, where many waterbodies are heavily modified and sections of river are channelized, increasing the risk of fish species having to combat high water velocities during peak flow events. An example of this is the river channel at Lomeshaye on Pendle Water (Figure 3.1.6). This location has been selected for a re- naturalisation project which will remove the fluming effects of the channel and improve the river connectivity and habitat quality. This reduction in water velocity will help conserve the energy of migrating fish and also reduce the risk of redd wash out in high flow events. Figure 3.1.6. Lomeshaye river channel on Pendle Water
Urban environments are also thought to exacerbate river temperatures, with large scale discharges from sewage treatment works and industry effecting river temperatures, along with domestic discharges and warming resulting from runoff over paved surface. These are also sources of point and diffuse pollutants that are affecting our river environment and water quality.
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Figure 3.1.7. NFCS grade maps of the Calder Catchment for brown trout fry 2018 and 2019 14 | P a g e
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The Hodder Catchment
During the survey season in 2018 the Hodder 30 catchment was most affected by the drought 25 conditions with 31 out of 95 sites being delayed due 20 15 to low water levels and restricted flows between 10 features. 42% of sites on the Hodder catchment saw sites Number of 5 a decline in NFCS trout fry grade-scores in 0 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 comparison to 2017. For 2019 there has been Hodder brown trout grade change from 2018 to 2019 another drop-in recruitment with half of the sites Figure 3.1.8. NFCS grade change comparison of brown trout on the surveyed being absent of trout fry (Figure 3.1.8). The Hodder catchment 2018 to 2019 (0 = no change). most affected areas were observed on Chipping Brook, Cow Ark Brook and the River Dunsop (Figure 3.2.9) and the majority of sites have been recorded as having poor to very poor densities. Sites above Stocks Reservoir have also failed to produce good trout fry densities in comparison to 2018. Habitat that is fragmented can limit a population size and reduce genetic variability; this can leave isolated populations vulnerable to extreme events, and recovery is slower due to the lack of connectivity and free movement between tributaries and main stem rivers.
Sea trout were recorded on the River Dunsop (Figure 3.1.9) in the last week of August after spate events. It is rare to capture sea trout in RRT surveys and to observe them in 2019 is a positive after the prolonged low waters during last year’s peak migration time. River discharge and water levels play an important role in both timing and success of fish ascent, and sea trout can contribute to a large proportion of egg production during spawning in comparison to resident fish.
Previously sites on the rivers Brennand and Whitendale have been surveyed by the Environment Figure 3.1.9. Sea trout caught in RRT surveys 2019 Agency as part of their monitoring of Restoring Sustainable Abstraction. This programme ended in 2018 and select sites will be added to the Ribble Rivers Trust’s survey list for 2020 to ensure that these tributaries have good coverage and are represented in the dataset.
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Figure 3.1.10. NFCS grade maps of the Hodder Catchment for brown trout fry 2018 and 2019
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The Lower Ribble Catchment
In comparison to 2018 there has been a reduction in brown trout grades in the tributaries from the tidal limit to Calder Foot. 17 out of the 21 sites surveyed were devoid of salmonids and in 2019 Dean Brook, Boyce’s Brook and Duddel Brook were the only tributaries that produced brown trout fry (Figure 3.1.4). The Lower Ribble consists of many low Strahler Stream Order rivers and hold poor spawning habitat and many sites are not naturally optimised for salmonid spawning due to slope and substrate composition. Of the tributaries that do hold suitable habitat, good numbers of trout fry have been recorded in previous years, and improvements to fish passage and water quality will only promote recruitment on this catchment.
Figure 3.1.11 NFCS grade maps of the Lower Ribble Catchment for brown trout fry 2018
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The Mid-Ribble Catchment
The tributaries and main stem between Calder Foot 40 and Paythorne Bridge, only produced 3 ‘Fair’ and 2 30 ‘Good’ trout fry grades in the 2019 surveys (Figure 20 3.1.14). There has been a 50% reduction in the grade 10
score densities of sites surveyed in 2018 and 2019 sites Number of
(Figure 3.2.10) and this year 59% of Mid-Ribble sites 0 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 were absent of trout fry. Mid-Ribble brown trout grade change from 2018 to 2019 This year Ings Beck produced worrying results, as Figure 3.2.12. NFCS grade change comparison of brown trout on the Mid- Ribble catchment 2018 to 2019 (0 = no change). these sites rarely fall below A and B NFCS grades. Pendleton Brook, another tributary that holds good spawning potential has also had a large decrease in recruitment, and Tosside and Bond Beck are a similar story producing ‘poor’ and ‘very poor’ NFCS grades (see Figure 3.2.11). Of the sites that have produced trout fry, these are in low densities and this will have an impact on the number of fish that are to survive to become the adult spawning population in the future.
Another example of an isolated trout population on the Ribble catchment is Mearley Brook. Without intervention, trout on this brook may easily proceed to extinction as a consequence of a reduction in population size and genetic variability. The Primrose Lodge Blue and Greenway project seeks to deliver improvement works to support the enhancement of the ecological function, and conservation status of the water body. As part of the works a fish pass solution has been designed to reconnect the main stem Ribble to Mearley Brook for the first time in 230 years. This will allow for the reintroduction of genetic diversity and improve the resilience of the trout population. Future fish passage works is also needed on the neighboring Pendleton Brook, to ensure that all tributaries of the local sub-catchment have improved connectivity.
Figure 3.2.13 Primrose lodge pond weir on Mearley Brook 2019 (left) and brown trout parr (right) captured in 2019 surveys
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Figure 3.1.14. NFCS grade maps of the Mid-Ribble Catchment for brown trout fry 2018 and 2019
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The Upper Ribble Catchment
The main stem and tributaries from Paythone Bridge 14 to Ribble head has also seen poor densities of brown 12 trout fry, with 88% of sites producing poor or no 10 8 young of year for 2019. Rathmell and Wiggleswoth 6
beck which have previously provided some of the 4 Number sites Number of best trout results on the Upper-Ribble and are 2 0 relatively consistent in delivering good results have -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 had some of the worst reductions in NFCS grade Upper Ribble brown trout grade change from 2018 to 2019 scores compared to 2018 (Figure 3.1.15). The only Figure 3.1.15. NFCS grade maps of the Mid-Ribble Catchment for brown trout improvements seen on the catchment from last year has been on Brants Ghyll and Tems Beck (Figure 3.1.17) but results on these tributaries are below their long- term average.
Sites above Stainforth Force have produced minimal fry densities with the majority of surveys recording no trout fry present. At the top of the catchment, Cam and Gayle are exposed rivers which have suffered from habitat degradation, through historic tree clearance and channel modification. The planting and habitat creation which is planned for Gayle Beck over the next 2 years will provide more complex habitat by installing tree stems and engineered log jams. These features will cause scour pools and riffle sections to form, increasing in-channel geomorphological diversity and improve spawning, nursery and on growing habitat. This area will also benefit from the riparian planting, as an MSc study carried out by Queen Mary University of London has shown that RRT planting schemes have positive indications of increased resilience in invertebrate food webs
Figure 3.1.16 Simplified habitat of Gayle Beck near Ribble Head. The river has been straightened and stripped of riparian cover/habitat.
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Figure 3.1.17. NFCS grade maps of the Upper Ribble Catchment for brown trout fry 2018 and 2019
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3.2 Atlantic Salmon (Salmo salar) During the 2019 surveys, a total of 672 salmon fry and parr were captured in 55 out of 328 electric fishing sites. This is a decrease of 477 individuals in comparison with the 2018 surveys and the lowest number of salmon recorded by the trust in 12 years of monitoring. The Ribble, once considered a premium English salmon water, is very much a salmon population that is at risk.
180 160 140 120 100 80 60 40 Cumulative NFCS NFCS Cumulative gradescore 20 0 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Atlantic salmon Figure 3.2.1. Cumulative NFCS grade-score and total calculated fry/100m² for the catchments 158 electric fishing sites holding 10 years of consecutive data for Atlantic salmon 2010 - 2019. The year on year decline of the cumulative grade score is driven by the loss of low-density sites which has narrowed the recorded distribution of salmon spawning. Sites that have also been classed as ‘strongholds’ for Atlantic salmon are also being impacted by poor returns. These areas must be protected and an increase in conservational efforts must be applied to improve habitat and water quality for the long-term sustainability of this species. Degradation of Atlantic salmon populations at this rate may lead to unrecoverable numbers and local extinction on the Ribble and its sub-catchments.
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Cumulative NFCS NFCS Cumulative gradescore 10 0 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019
Calder Hodder Ribble Figure 3.2.2. Total grade-score for sub-catchments electric fishing sites with 10 years of consecutive data for Atlantic salmon 2010 to 2019.
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Figure 3.2.3. Catchment map [1:250,000] showing Atlantic salmon fry NFCS grades from surveys undertaken by RRT in 2018. Green – red points indicate higher to low grades. Black indicates an absence of salmon fry.
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Figure 3.2.4. Catchment map [1:250,000] showing Atlantic salmon fry NFCS grades from surveys undertaken by RRT in 2019. Green – red points indicate higher to low grades. Black indicates an absence of salmon fry.
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The Calder Catchment
This year on the Calder catchment only 2 salmon parr were recorded and no salmon fry were observed. As seen in the trout results, 2019 has been an exceptionally poor year for fry recruitment, however, the Calder is consistently a poor catchment for salmon spawning. Limited waterbodies and sites yield regular fry results with Sabden and Hyndburn Brooks being the only two tributaries in which salmon fry are being repeatedly recorded. These sites are historic spawning areas which were established before the removal of Padiham Weir. Current RRT survey locations are failing to identify an increased and sustainable distribution of salmon spawning on the Calder Figure 3.2.5. Salmon parr captured on the lower reaches of catchment due to their low abundance. Environmental DNA Sabden Brook 2019 sampling has been carried out in 2019 to try and identify the potential upstream limits of salmon on the catchment. Environmental DNA has been classed as conservation in a cup of water, where the presence of a species can be identified in a river environment by targeting unique sequences of their DNA fingerprint. Initial results have shown indications that Atlantic salmon are present on Pendle water, but their lifecycle stage cannot be determined, as we don’t know if the DNA detected is from fry, parr or returning adult salmon. Additional electric fishing sites will be explored in 2020 to try and identify if any spawning has been successful on Pendle Water or find the presence of parr.
Figure 3.2.6 Kate Morgan eDNA sampling on the main stem Ribble (left) eDNA results from Pendle Water (right) showing signal strength of the DNA fingerprint of 18 species. Species observed present where circles are.
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The Hodder Catchment
It seems there has been little change on the Hodder 70 catchment from the long-term trends (Figure 3.2.2), 60 50 however, this only shows the sites that have 10years 40 of consecutive data, there are holes in the data set 30 20
representing sites on the River Dunsop, Brennand sites Number of 10 and Whitendale. These tributaries are classed as 0 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 strong hold sites which regularly produce good Hodder Atlantic salmon grade from 2018 to 2019 densities of young, but this year the River Dunsop Figure 3.2.7. NFCS grade change comparison of Atlantic salmon on the Hodder catchment 2017 to 2018 (0 = no change). has seen some of the largest reductions in NFCS grade scores on the Hodder catchment (Figure 3.3.5). Previously sites on the rivers Brennand and Whitendale have been surveyed by the Environment Agency as part of their monitoring of Restoring Sustainable Abstraction. This programme ended in 2018 and select sites will be added to the Ribble Rivers Trust’s survey list for 2020 to ensure that these tributaries have good coverage and are represented in the dataset.
Comparing the results generated in 2018 and 2019 (Figure 3.3.5 and 3.3.6), sites that have seen no change in NFCS grades are all recorded as ‘very poor’ or have had no salmon fry recorded in both years. As well as the River Dunsop large grade reductions have been seen on the main stem Hodder downstream of Newton Bridge, which have been previously recorded as NFCS B and C grades, now producing F and E grades.
Sites on the Chipping and Lower Loud sub-catchments have been lost in 2019 after degrading over the past 11years. This has reduced the recorded distribution of Atlantic salmon fry to sites above the confluence of Langden Brook and River Hodder (Figure 3.3.6). For 2019 there are only 3 A grade sites recorded, 2 of which are on the main stem River Hodder below Slaidburn and the other is the lowest site on Croasdale Brook. Croasdale Brook has seen a positive NFCS grade increase on its lower sites from C to A and F to D. Other improvements recorded on the catchment are minimal and mostly limited to long Figure 3.2.8. River Dunsop 2019 fisheries surveys term low density sites. Numbers of parr on the river Dunsop have been positive, even if the fry numbers reflect a failing population.
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Figure 3.2.9. NFCS grade maps of the Hodder Catchment for Atlantic salmon fry 2018 and 2019
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The Mid-Ribble Catchment
The tributaries and main stem between Calder Foot 80 and Paythorne Bridge, only produced one NFCS C- grade out of 87 sites surveyed on the Mid-Ribble. All 60 other sites that produced Atlantic salmon fry were 40
classed as having ‘poor’ or ‘very poor’ densities and 20 Number sites Number of 87% of sites on the Mid-Ribble were absent of 0 Salmon fry. -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 Mid-Ribble Atlantic salmon grade from 2018 to 2019 From RRT survey results the Mid-Ribble has Figure 3.2.10. NFCS grade change comparison of Atlantic salmon on the Mid- historically never produced large densities of Ribble catchment 2018 to 2019 (0 = no change). Atlantic salmon young, and distribution has mainly been limited to the sub-catchments of Skirden, Swanside and the bottom of Mearley. These sub-catchments suffer from pressures of agriculture, point source pollution and urbanisation, as well as habitat degradation. Over time the densities of salmon young have continued to decline and sites at the bottom of Mearley now regularly produce no signs of successful spawning. As described in 3.2, Brown Trout on the Mid-Ribble, a fish pass solution has been designed to reconnect the main stem Ribble to Mearley Brook for the first time in 230 years. For salmon, this will unlock a large length of catchment to repopulate. But to have a future, and to provide a sustainable population, improvements to habitat and water quality must compliment current conservational efforts.
Atlantic salmon have been recorded spawning by the trust for the first time in West Bradford Brook, above a 2018 fish pass. It is thought that salmon could get to this location previously in elevated flows, but this is the first salmon fry recorded in 12 years of electric fishing surveys.
Figure 3.2.11. Atlantic salmon fry (right) captured in the 2019 electric fishing survey above the West Bradford Brook fish pass (center)
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Figure 3.2.12. NFCS grade maps of the Mid-Ribble Catchment for Atlantic salmon fry 2018 and 2019
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The Upper Ribble Catchment
Out of the 43 sites that were surveyed on the Upper 25 Ribble, 18 sites recorded ‘poor’ and ‘very poor’ Atlantic 20 salmon NFCS grades. Only a single site for 2019 was 15 10 recorded as ‘Excellent’ for the whole Ribble Catchment, on 5 the main Stem Ribble at Nappa (Figure 3.3.10). sites Number of 0 Like other catchments, sites that have dropped to F grade -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 Upper Ribble Atlantic salmon grade from 2018 to sites are those recorded as having low-density grades in 2019 2018. These low-density sites are extremely vulnerable, Figure 3.2.13. NFCS grade change comparison of Atlantic salmon on the Upper Ribble catchment 2018 to 2019 (0 = no change). and their presence is not foreseeable in the future especially if returns of spawning fish and the water and habitat quality continue to decline.
Stainforth Force is one of the largest natural barriers that Salmon on the Ribble catchment have to navigate to reach their spawning ground. For the time Salmon spend in river 50 to 70% of their energy is used during river migrations from estuary to spawning. Manmade river obstacles directly increase energy consumption which will ultimately have a negative impact on migration and reproductive success. The Ribble Trust is working towards removing and reducing the effects of manmade barriers on the catchment and allowing migratory fish to have enough energy reserves to ascend natural river features. There are large areas in which monitoring is not capturing data on the Upper Ribble and it has been suggested that a large proportion of salmon stocks spawn on the main stem. Figure 3.2.14. Salmon leaping at Stainforth Force For the Upper Ribble, the distribution of electric fishing sites is limited to smaller tributaries and select main stem sites. There are restrictions in the addition of sites to capture areas above Settle and Horton-In-Ribblesdale due to access and river morphology affecting the ability to electric fish
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Figure 3.2.15. NFCS grade maps of the Upper Ribble Catchment for Atlantic salmon fry 2018 and 2019
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3.3 Other Species
The Ribble Trusts monitoring 90 programme targets brown trout and 80 70 Atlantic salmon fry as keystone 60 indicator species of a catchment’s 50 40 health. However, other non-target % of sites %of 30 species captured during surveys can 20 provide useful information to direct 10 0 conservation efforts. Quantifiable Bullhead Stoneloach Minnow Stickleback Eels calculation methods are not used on 2016 2017 2018 2019 semi-quantitative surveys for by-catch Figure 3.3.1. Dominant by-catch by species % presence of sites from 2016 to 2019. species; therefore presence/absence data must be used. 7 6 Bullhead (Cottus gobio) remain 5 the dominant non-targeted 4
species on the catchment found 3 % of of % sites within 79% of sites (Figure 3.3.1 2 1 and 3.3.2). This annex II species is 0 rare in some parts of England but Brook Grayling Gudgeon Perch Chub Roach Dace Lamprey the Ribble is a stronghold for this 2016 2017 2018 2019 fish which holds conservational Figure 3.3.2. Accompanying by-catch by species % presence of sites from 2016 to 2019. interest. The number of European eel (Anguilla anguilla) caught as by-catch by the Ribble Trust has seen an annual decrease over the past five years. This reduction does not truly reflect the population as they are not a targeted species, but the reduction is worth noting as this species is classed as critically endangered (Jacoby & Gollock, 2014) . If we are to understand more about the habitat, movement and populations of eels within the catchment, a more targeted surveying approach would be required.
From survey sites that were affected by the drought conditions in 2018, a number were flagged for the monitoring of returns of by-catch species that have a slow dispersal and are more affected by migration barriers. Downham, Heys and Chatburn Brook on Mid-Ribble is an isolated tributary link cut off from the main Ribble by impassible natural and manmade barriers. Because of this there has been no change in species presence/absence and its long-term viability is uncertain. Hesley Beck, another dry site in 2018 has seen bullhead and trout return to the area and the same has been reported on Bond Beck.
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Areas of conservational and species importance can be highlighted through the presence/absence of all fish species. Using ArcGIS 10.3.1, point density analysis can be used to produce an average magnitude-per-unit area from site data that fall within a neighborhood defined by a distance from each site (Figure 3.4.3). Using data in this way can help direct strategies to protect areas of spawning importance and also highlight areas that are failing to reach their full ecological potential, i.e. the tributaries of the lower Ribble are found to be poor spawning habitat for salmonids and are mainly dominated by other species. The lower reaches on Bezza Brook were a hot spot for species richness in 2018, holding nursery habitat for coarse species. With improvements in connectivity for non-salmonid species in the lower reaches there could be further dispersal and utilization of habitat and neighboring tributaries.
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Figure 3.3.3. Catchment map [1:250,000] showing 2018 and 2018 electric fishing sites (black) and the average point density calculated from a magnitude-per-unit area based on the total fish species richness of each site that falls within with a neighborhood of 2500m 34 | P a g e
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3.4 Length-Weight Relationships and Biomass
The Ribble Rivers Trust’s electric fishing programme is a primary tool in the long-term assessment of sustainable catchment restoration. This method maps the distribution and abundance of keystone salmonid species which are indicators of the ecological status and connectivity of the riverine system. To improve the ability to direct Figure 3.4.1 Measured standard length, fork length and maximum total and evaluate management strategies, the length of fish (brown trout pictured). condition of developing salmonids can be observed via their length-weight relationship. During the Ribble Rivers Trust’s electric fishing surveys, fork length distribution is used to differentiate between the young of year, parr and adult age classes. To further understand the condition of Ribble salmonids the wetted weights of individuals were recorded in the 2018 and 2019 quantitative surveys, along with the total mass of each by-catch species. It is advised not to include the juvenile population in the analysis of length-weight, however the young of year will be included in the total weight described in Figure 3.5.6 and 3.5.7. Ideally, surveys would be carried out in the same locations over sequential months to monitor dispersal, survival and growth patterns. Single point analysis can provide a snapshot into the condition of salmonids and the other species that inhabit the reach.
Condition Factor Considering that the number of salmon parr recorded within quantitative Fulton condition factor surveys are minimal, the focus of condition will be on brown trout only. As 3 the majority of individuals spend their lifecycle residing in the river system, Where: W = actual퐾 = 100 weight× W/퐿 (g), L = total fork they are also the best keystone indicators for the catchment. For this length (cm) analysis, condition must not be considered as the health of an individual but as the relationship between length and weight, which is traditionally characterised by Fultons condition factor (1904): Ricker modified condition factor
This equation assumes isometric growth; however, it has been shown that 푏 fish often grow allometrically which increases the scatter around the mean Where: b is a퐾′ constant = 100 determined × 푊/퐿 from the length-weight relationship (Figure 4.4): condition (K) of a population. To reduce the effects of allometry from the estimation of fish condition, the Ricker (1951) modified condition factor K’ 푏 is used: 푌 = 푎푋
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140 y = 0.0103x3.0563 R² = 0.9334 120
100
80
Weight (g) Weight 60
40
20
0 0 5 10 15 20 25 Fork Length (cm)
Figure 3.4.2 Length-weight relationship of +1-year brown trout caught in quantitative surveys on the Ribble catchments 2018.
2.9926 400 y = 0.0121x R² = 0.9227
350
300
250
200 Weight (g) Weight 150
100
50
0 0 5 10 15 20 25 30 35 Brown trout fork length (cm)
Figure 3.4.3 Length-weight relationship of +1-year brown trout caught in quantitative surveys on the Ribble catchments 2019.
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With the use of a scaling factor, the results of K and K’ normal condition is expressed as 1, for K’ this result shows that an individual fall within the expected condition defined by trout from the Ribble catchment (Figure 3.5.2 and 3.5.3). Where condition is >1 fish have a higher expected mass to fork length and <1 fish have a lower expected mass to fork length. By compiling results, we can visually identify catchments that have outliers of poor condition and identify sites where the carrying capacity and condition of individuals might be affected by lack of resources and habitat complexity (Figure 3.5.4).
Figure 3.4.4 Rickers modified condition factor (K') for the sub-catchments of the Ribble and for quantitative sites on the Calder catchment 2018 (above) 2019 (below). The plot shows the range of condition, lower and upper quartiles and median. The mean condition is marked as X.
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From the length-weight relationship of Ribble brown trout we can create an Expected weight from length equation to give an expected weight based on an individual’s length. Expected weight and actual weight can be compared to identify individuals 푏 Where: L = total fork^푤 length = 푎퐿 (cm), a and b are that are outside the catchment trend (Figure 3.5.5). derived from Figure 4.4
350 y = 1.0554x - 1.9024 300 R² = 0.9458
250
200
150
Calculated (g) weight 100
50
0 0 50 100 150 200 250 300 Actual weight (g)
400 y = 0.9999x - 0.3326 R² = 0.9642 350
300
250
200
150 Calculated (g) weight 100
50
0 0 50 100 150 200 250 300 350 400 Actual weight (g)
Figure 3.4.5 Actual weight vs calculated expected weight derived from fork length for 2018 (above) and 2019 (below).
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Biomass The total biomass of fish in a stream is influenced by physical, chemical and biological characteristics of a waterbody (Warren, et al., 2010). Decreases in fish biomass have been linked to limited in-stream productivity of macro-invertebrate abundance and a reduction in terrestrial subsidies (Thomas, et al., 2015). By plotting biomass per unit area for each species areas of species richness and productivity can be ascertained (Figure 3.5.6 and 3.5.7).
Figure 3.4.6. Percentage of species in 2018 quantitative surveys where the area of the chart is equal to the total biomass per 100m² ranging from 263.15 - 1641.32 g/100m²
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Figure 3.4.7. Percentage of species in 2019 quantitative surveys where the area of the chart is equal to the total biomass per 100m² ranging from 263.15 - 1641.32 g/100m²
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4.0 Discussion
With anthropogenic driven climate change, we are seeing more extreme weather patterns, increased probability of high rainfall events and longer dry periods. With 2018 summer dominated by warm weather and below average rainfall, drought conditions were seen across the Ribble catchment. Mean temperatures of 17.2°C were documented by the Met Office making it the hottest summer on record. There were concerns for the +0 salmonids targeted during the 2018 survey season, as fry are more sensitive to extremely low flows due to poor mobility and ability to seek refuge, and their susceptibility to high water temperatures. Overall, the UK had 48% of average rainfall of the 1981-2010 average during the summer months and by the end of October groundwater and river levels remained below average. Summer 2018’s lowest flows coincided with the main run of sea trout in July and in the Autumn months minimal spate events took place from the end of September (Figure 5.1) 6 2018 Average Level 2017 Average Level 5
4
3
GAUGE 2
1
0 J F M A M J J A S O N D A E A P A U U U E C O E N B R R Y N L G P T V C
Figure 5.1 Average river levels on the River Ribble at Samlesbury, January - December 2017 & 2018.
February 2019 saw unseasonably warm weather and was recorded as the hottest on record for the UK. Rainfall was exceptionally high for the North West in March with Storms Freya, Gareth and Hannah bringing bands of heavy rain fall and high winds. This resulted in flood warnings being issued and some of the highest river levels recorded since the winter of 2015 (Figure 5.2). By the month-end, half of the hydrological areas in North West England had observed around twice the expected monthly rainfall for March.
6 2019 Average Level 2019 Max Level 5 4
3 GAUGE 2 1 0 J F M A M J J A S O N A E A P A U U U E C O N B R R Y N L G P T V
Figure 5.2. Average and max river levels of the River Ribble, January to October 6th, 2019
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The timing and patterns of emergence and the size of emerging fish has high importance on their subsequent establishment of feeding territory, further dispersal and survival potential (Nika, 2013). Mortality bottlenecks for many species occur in juvenile stages and are thought to result from limitations of food or foraging habitat during a "critical period" for growth and survival (Kennedy, et al., 2008). For salmonids the largest proportion of mortalities occur during the first weeks of fry emergence after depletion of yolk reserves and exogenous feeding begins. These high flow events in March 2019 occurred at this critical time for salmonid development. Mortalities of salmonids can increase significantly with high discharge events due to their size affecting swimming ability (Jensen & Johnsen, 1999). Events like this also have a negative effect on growth as spate events reduce the abundance of food.
In combination with 2015 flood events, we have recorded the worst fry recruitment on the catchment in 12 years of surveys. Although fish communities have evolved to withstand the dynamic nature of a river habitat and are relatively resilient to high hydrological events, severe floods and extreme low flows at critical life-cycle stages influence community composition which have short and long term affects, especially when looking at species of concern. It is predicted that this year’s low fry abundance will have an influence on the next generation of fish, and we will also see the short-term effects in 2020 when observing the abundance of parr.
For Atlantic salmon we are seeing a year on year decline in recruitment. Salmon have a highly complex life cycle that is impacted at every stage by resource competition, environmental stochasticity and anthropogenic pressures. There is no golden bullet to solve these issues and to have a chance of improving stock of salmon on the Ribble catchment, more needs to be done to reverse negative effects.
The Ribble Rivers Trust: The Future of our work
Our catchment is suffering from the effect of anthropogenic pressures and climate change. The Ribble Trust will continue to improve the water environments of the catchment, by restoring and protecting the river to make sure that future generations can enjoy the beauty of its flora and fauna.
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5.0 References Arevalo, E. et al., 2018. Effect of food shortage and temperature on age 0+salmonids: a contribution to predict the effects of climatechange. Journal of Fish Biology, pp. 642-652. Armstrong, J. D., Braithwaite, V. A. & Fox, M., 1998. The response of wild Atlantic salmonparr to acute reductions in water flow.. Journal of Animal Ecology, Volume 67, pp. 292-297. Baldigo, B. P. & Warren, D. R., 2008. Detecting the Response of Fish Assemblages to Stream Restoration: Effects of Different Sampling Designs. North American Journal of Fisheries Management, 28(3), pp. 919-934. Caissie, D., 2006. The thermal regime of rivers: A review. Freshwater Biology, 51(8), pp. 1389-1406. Crozier, W. W. & Kennedy, G. J. A., 1994. Application of semi-quantitative electrofishing to juvenile salmonid stock surveys. Journal of Fish Biology, 45(1), pp. 159-164. Dugdale, S. J., Bergeron, N. E. & St-Hilaire, A., 2013. Temporal variability of thermal refuges and water temperature patterns in an Atlantic salmon river. Remote Sensing of Environment, Volume 136, pp. 358-373. Elliott, J. M. & Elliott, J. A., 2006. A 35-year study of stock-recruitment relationships in asmall population of sea trout: assumptions, implications and limitations for predicting targets. In: G. Harris & N. Milner, eds. Sea Trout: Biology, Conservation and Management. Oxford: Blackwell Publishing, pp. 257-278. Elliott, J. M. & Elliott, J. A., 2010. Temperature requirements of Atlantic salmon Salmo salar, brown trout Salmo trutta and Arctic charr Salvelinus alpinus: Predicting the effects of climate change. Journal of Fish Biology, 77(8), pp. 1793- 1817. Fredrich, F., Ohmann, S., Curio, B. & Kirschbaum, F., 2003. Spawning migrations of chub in the River Spree, Germany. Journal of FishBiology, Volume 63, pp. 710-723. Fulton, T. W., 1904. The rate of growth of fishes.. 22nd Annual Report of the Fishery Board of Scotland, Issue 3, pp. 141-241.
Jacoby, D. & Gollock, M., 2014. Anguilla anguilla. The IUCN Red List of Threatened Species 2014. [Online] Available at: https://www.iucnredlist.org/species/60344/45833138 [Accessed 20 November 2019]. Kennedy, B. P., Nislow, K. H. & Folt, C. L., 2008. Habitat-Mediated foraging limitations Drive Survival Bottlenecks For Juvenile Salmom. Ecology, 89(9), pp. 2529-2541. Landergren, P., 2004. Factors affecting early migration of sea trout Salmo trutta parr tobrackish water.. Fisheries Research, Volume 67, p. 283–294. Le Cren, E. D., 1951. The length – weight relationship and seasonalcycle in gonad weight and condition in the perch (Percafluviatilis). Journal of Animal Ecology, Volume 20, pp. 2-19. Ricker, W. E., 1951. Chapter 9. Growth in Length and in Weight. In: W. E. Ricker, ed. Computation and interpretation of the biological statistics of fish populations.. Ottawa : Fisheries Research Board of Canada, pp. 1-382. Solomon, D. J. & Lightfoot, G. W., 2008. The thermal biology of brown trout and Atlantic salmon, Bristol: Environment Agency.
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Thomas, S. M., Griffiths, S. W. & Ormerod, S. J., 2015. Adapting streams for climate change using riparian broadleaf trees and its consequences for stream salmonids. Freshwater Biology, 61(1), pp. 64-77. Thomas, S. M., Griffiths, S. W. & Ormerod, S. J., 2015. Adapting streams for climate change using riparian broadleaf trees and its consequences for stream salmonids.. Freshwater Biology, 60(1), pp. 64-77. Warren, D. R., Mineau, M. M., Ward, E. J. & Kraft, C. E., 2010. Relating fish biomass to habitat and chemistry in headwater streams. Environmental Biology of Fishes, Volume 88, pp. 51-61.
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6.0 Appendices 6.1 Appendix A 350
300
250
200
150
100
Cumulative NFCS NFCS Cumulative gradescore 50
0 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019
Trout grade
Appendix A. 1. Cumulative NFCS grade-score for the catchments core 94 electric fishing sites for brown trout 2008 - 2019.
140
120
100
80
60
40
Cumulative NFCS NFCS Cumulative gradescore 20
0 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Atlantic salmon
Appendix A. 2. Cumulative NFCS grade-score for the catchments core 94 electric fishing sites for Atlantic salmon 2008 - 2019.
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6.2 Appendix B
Appendix B. 1. Fork length histogram of all brown trout captured on the Calder catchment 2019. Maximum fork length for 0-year trout = 95 mm at time of survey.
Appendix B. 2. Fork length histogram of all brown trout captured on the Hodder catchment 2019. Maximum fork length for 0-year trout = 96 mm at time of survey.
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Appendix B. 3. Fork length histogram of all brown trout captured on the Lower Ribble catchment 2019. Maximum fork length for 0-year trout = 98 mm at time of survey.
Appendix B. 4. Fork length histogram of all brown trout captured on the Mid-Ribble catchment 2019. Maximum fork length for 0-year trout = 99 mm at time of survey.
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Appendix B. 5. Fork length histogram of all brown trout captured on the Upper Ribble catchment 2019. Maximum fork length for 0-year trout = 100 mm at time of survey.
Appendix B. 5. Fork length histogram of all Atlantic salmon captured on the Hodder catchment 2019. Maximum fork length for 0-year salmon = 98 mm at time of survey
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Appendix B.6. Fork length histogram of all Atlantic salmon captured on the Mid-Ribble catchment 2019. Maximum fork length for 0-year salmon = 100 mm at time of survey
Appendix B.7. Fork length histogram of all Atlantic salmon captured on the Upper Ribble catchment 2019. Maximum fork length for 0-year salmon = 100 mm at time of survey
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6.3 Appendix C 5 y = 1.1823x + 0.3409 R² = 0.9282 4.5 4
2 3.5 3 2.5 2
1.5 LN(y+1) fry/100m 1 0.5 0 0 0.5 1 1.5 2 2.5 3 3.5 4 LN(x+1) Fry/5min
Appendix C. 1 Brown trout quantitative fry population relationship between semi-quantitative (5 minutes fry capture) and quantitative electric fishing results (Fry per 100 square) that is LN+1 transformed. Fitted linear regression for 0 + salmonids is produced where Ln (y + 1) = 0.3409 + 1.1823 Ln (x + 1)
3.5 y = 1.3992x + 0.0228 R² = 0.9578 3
2 2.5
2
1.5
LN(y+1) Fry/100m 1
0.5
0 0 0.5 1 1.5 2 2.5 ln(x+1) Fry/5min
Appendix C. 2. Atlantic salmon quantitative fry population relationship between semi-quantitative (5 minutes fry capture) and quantitative electric fishing results (Fry per 100 square) that is LN+1 transformed. Fitted linear regression for 0 + salmonids is produced where Ln (y + 1) = 0.0228 + 1.3992 Ln (x + 1)
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